Editing Swimfin (section)

=== Paddle vs split ===
[[File:Jetfins reglables.jpg|thumb|An open-heel vented paddle Jetfin]]
Paddle fins have simple plastic, composite, or rubber blades that work as extensions of the feet while kicking. Some paddle fins have channels and grooves claimed to improve power and efficiency though it has been shown that the desired effect does not usually occur.<ref name="pmid9148086"/><ref>{{cite journal |author=McMurray RG |title=Competitive efficiencies of conventional and super-swinfin designs |journal=Hum Factors |volume=19 |issue= 5|pages=495–501 |year=1977 |doi= 10.1177/001872087701900505|s2cid=110632429 }}</ref> Relatively stiff paddle fins are widely believed to be the most versatile and have improved swimming economy in men.<ref name="pendergast2003" /><ref name="pmid16341874">{{cite journal |vauthors=Zamparo P, Pendergast DR, Termin A, Minetti AE |title=Economy and efficiency of swimming at the surface with fins of different size and stiffness |journal=Eur. J. Appl. Physiol. |volume=96 |issue=4 |pages=459–70 |date=March 2006 |pmid=16341874 |doi=10.1007/s00421-005-0075-7|s2cid=34505861 }}</ref> Tests in women showed a more flexible fin to be more economical, most likely due to lower leg power.<ref name="pmid9148086"/><ref name="pmid12841610">{{cite journal |vauthors=Pendergast DR, Mollendorf J, Logue C, Samimy S |title=Underwater fin swimming in women with reference to fin selection |journal=Undersea Hyperb Med |volume=30 |issue=1 |pages=75–85 |year=2003 |pmid=12841610 |url=http://archive.rubicon-foundation.org/3935 |archive-url=https://web.archive.org/web/20090709194405/http://archive.rubicon-foundation.org/3935 |url-status=usurped |archive-date=July 9, 2009 |access-date=2008-08-25}}</ref> Stiff paddle fins are required for certain types of kicks — such as [[back kick]]s and [[helicopter turn]]s — performed by scuba divers trained in [[cave diving]] and [[wreck diving]] to avoid stirring up sediment.

Some swimfins have a split along the centreline of the blade. The manufacturers claim that split fins operate similarly to a [[propeller]], by creating [[Lift (force)|lift]] forces to move the swimmer forwards.<ref name="apollo">{{cite web |url=http://www.apollosportsusa.com/Products/Fins/Principles.htm |author=Apollo Sports USA |title=Principles of Split Fin Operation |access-date=11 February 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100526123506/http://www.apollosportsusa.com/Products/Fins/Principles.htm |archive-date=26 May 2010 }}</ref> The claim is that water flowing toward the center of the fin's "paddle" portion also gains speed as it focuses, creating a "suction" force.<ref name="apollo" />  A 2003 study by Pendergast ''et al'' called this into question by showing that there was no significant change in performance for a particular split fin design when the split was taped over.<ref name="pendergast2003" /> The technology used in most commercial split fin designs is patented by the industrial design firm Nature's Wing, and is used under license.<ref>{{cite web|url=http://tribook.org/swim-fin/ |title=Swim Fin Patent Revised by New Wig in 1997|publisher=TriBook.org|access-date= 31 March 2002}}</ref>